The latest versions of this document, the PNG specification, and related information can always be found at the PNG FTP archive site, ftp://ftp.simplesystems.org/pub/png/. The maintainers of the PNG specification can be contacted by e-mail at png-mng-misc @ lists.sourceforge.net.
This document is the register of public chunks and keywords in the Portable Network Graphics (PNG) specification, version 1.2 [PNG-1.2], and in Portable Network Graphics (PNG) Specification (Second Edition) [PNG-ISO], plus any additional registered "public" PNG chunks and keywords, with their date of registration and location of their specifications.
Some chunks listed here are expected to be less widely supported than those defined in the basic specification. However, application authors are encouraged to use these chunk types whenever appropriate for their applications.
Additional chunk types and keywords may be proposed for inclusion in these lists by contacting the PNG specification maintainers at png-mng-misc @ lists.sourceforge.net.
This table lists the registered public PNG chunks.
Chunk Date Formal specification type registered of chunk type IDAT 7 Mar 95 PNG 1.2 IEND 7 Mar 95 PNG 1.2 IHDR 7 Mar 95 PNG 1.2 PLTE 7 Mar 95 PNG 1.2 bKGD 7 Mar 95 PNG 1.2 cHRM 7 Mar 95 PNG 1.2 dSIG 1 May 08 PNGEXT 1.4.0 fRAc 7 Mar 95[1] PNGEXT 1.2.0 gAMA 7 Mar 95 PNG 1.2 gIFg 7 Mar 95 PNGEXT 1.2.0 gIFt 7 Mar 95[2] PNGEXT 1.2.0 gIFx 7 Mar 95 PNGEXT 1.2.0 hIST 7 Mar 95 PNG 1.2 iCCP 17 Aug 98 PNG 1.2 iTXt 9 Feb 99 PNG 1.2 oFFs 7 Mar 95 PNGEXT 1.2.0 pCAL 28 Jan 97 PNGEXT 1.2.0 pHYs 7 Mar 95 PNG 1.2 sBIT 7 Mar 95 PNG 1.2 sCAL 7 Mar 95 PNGEXT 1.2.0 sPLT 9 Dec 96 PNG 1.2 sRGB 6 Nov 96 PNG 1.2 sTER 15 Apr 06 PNGEXT 1.3.0 tEXt 7 Mar 95 PNG 1.2 tRNS 7 Mar 95 PNG 1.2 zTXt 7 Mar 95 PNG 1.2 [1] The fRAc chunk was registered but never formally specified. [2] The gIFT chunk was formally deprecated on 23 Oct 98.
This table lists the keywords that have been registered for use in PNG textual chunks.
Keyword Date Formal specification
registered of keyword
Title 7 Mar 95 PNG-1.2
Author 7 Mar 95 PNG-1.2
Description 7 Mar 95 PNG-1.2
Collection 24 Jul 04 png-list archives
Copyright 7 Mar 95 PNG-1.2
Creation Time 7 Mar 95 PNG-1.2
Software 7 Mar 95 PNG-1.2
Disclaimer 7 Mar 95 PNG-1.2
Warning 7 Mar 95 PNG-1.2
Source 7 Mar 95 PNG-1.2
Comment 7 Mar 95 PNG-1.2
All registered textual keywords in iTXt and all other chunk types are limited to the ASCII characters A-Z, a-z, 0-9, space, and the following 20 symbols:
! " % & ' ( ) * + , - . / : ; < = > ? _
but not the remaining 12 symbols:
# $ @ [ \ ] ^ ` { | } ~
This restricted set is the ISO-646 "invariant" character set [ISO-646]. These characters have the same numeric codes in all ISO character sets, including all national variants of ASCII.
Copyright © 2000, 2006-2008, 2013 by: Glenn Randers-Pehrson
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